Abstract: A catalyst for acrylonitrile synthesis is disclosed which is composed of particles containing silica and a composite oxide including at least molybdenum. When the Mo/Si atomic ratio in bulk composition of the catalyst is represented by A and the Mo/Si atomic ratio in surface composition of the particles is represented by B, B/A is not more than 0.6.

Abstract: A catalyst for acrylonitrile synthesis is disclosed which is composed of particles containing silica and a composite oxide including at least molybdenum. When the Mo/Si atomic ratio in bulk composition of the catalyst is represented by A and the Mo/Si atomic ratio in surface composition of the particles is represented by B, B/A is not more than 0.6.

Abstract: A carbon-insertion-type palladium metal in which an amount of inserted carbon is 0.16 mol or more with respect to 1.0 mol of a palladium metal, and a carbon-insertion-type palladium metal in which a crystal face distance of a (111) face of a palladium metal is 2.270 ? or more are useful as raw materials of a palladium catalyst for use in an ?,?-unsaturated carboxylic acid preparation reaction, and the like. The carbon-insertion-type palladium metal can preferably be prepared by reduction of palladium in a palladium compound having a chlorine content of 0 to 300 ppm.

Abstract: A process for producing a supported catalyst for the synthesis of methacrolein and methacrylic acid in which a catalytic active substance comprising a composite oxide containing molybdenum and bismuth as essential components is supported on the inside surface and/or the outside surface of an inert carrier, which comprises the steps of drying a mixed solution or an aqueous slurry containing the compounds of the elements constituting the catalytic active substance, subjecting the dried product to a primary calcination at a temperature in a range of 200.degree.-400.degree. C. to form a catalytic active substance precursor, comminuting the obtained catalytic active substance precursor to such an extent that the medium particle size in the volume-based particle size distribution becomes 10 .mu.m or less, supporting the comminution product on an inert carrier, and subjecting it to a secondary calcination at a temperature which is 100.degree. C. or more higher than the primary calcination temperature.

Abstract: A process for producing a carbon fiber having a tenacity of 450 kg/mm.sup.2 or more, preferably 500 kg/mm.sup.2 or more, and a modulus of elasticity of 25 ton/mm.sup.2 or more which comprises subjecting a polyacrylonitrile-type fiber to a flame-resisting treatment in a flame-resisting treatment furnace provided with a plural number of driving rolls in an oxidizing atmosphere at 200.degree. to 400.degree. C. under application of multistep elongation, during said treatment the respective percentage of elongation in said multistep elongation being set respectively at a value which is equal to or within .+-.3% of the value of the percentage of elongation En indicating an inflection point Pn obtainable from the load and the percentage of elongation determined in advance by experimental measurements, and then subjecting the treated fiber to carbonization.